1. Field of the Invention
The present invention relates to a polishing pad and a method for making the same, and more particularly to a polishing pad having trenches and a method for making the same.
2. Description of the Related Art
FIG. 1 and FIG. 2 are schematic views of a method for making a conventional polishing pad. Referring to FIG. 1, polyurethane resin is formed on an upper surface 101 of a non-woven fabric 10. Next, the non-woven fabric 10 and the polyurethane resin are immersed in a curing liquid, to cure the polyurethane resin, thereby forming a grinding layer 12, where the grinding layer 12 has an upper surface 121 and a plurality of cells 14.
Next, a plurality of trenches 13 is formed on the upper surface 121 of the grinding layer 12 through laser or cutting. Subsequently, the upper surface 121 of the grinding layer 12 is ground with sandpaper, so as to produce a sense of fluff, and each of the cells 14 has an opening on the upper surface 121 of the grinding layer 12. Finally, a back adhesive layer 16 is bonded to a lower surface 102 of the non-woven fabric 10, to make a polishing pad 1.
The conventional polishing pad 1 has the following disadvantages. Firstly, the trenches 13 are formed through laser or cutting, thus, fringes 17 may be formed on sidewalls of the trenches 13 in this manner, and debris 18 remains on bottom walls of the trenches 13. When the polishing pad 1 is applied in a polishing process, the fringes 17 and the debris 18 may directly contact a workpiece to be polished to scratch the workpiece to be polished, resulting in scratch defects. Secondly, the space of a lower part of each cell 14 is larger than the space of an upper part of the cell 14. When the trenches 13 are formed, the upper parts of the cells 14 are removed, but the lower parts of the cells 14 remain, and thus a large amount of solid portions of the grinding layer 12 is removed, resulting in that the structural strength of the grinding layer 12 declines and a peeling damage occurs earlier, thereby reducing the service life of the polishing pad 1. Thirdly, the non-woven fabric 10 becomes brittle due to variation of fabric density distribution and permeation of the slurry, which easily results in that a part of the back adhesive layer 16 remains on a disc surface of a grinding device when the polishing pad 1 is replaced.
Therefore, it is necessary to provide an innovative and progressive polishing pad and a method for making the same, so as to solve the above problems.